Well thats a funny question because hash rate varies from card to card.....Despite they a all the same and with absolute identical settings and everything, my best card returns back about 3300 kH/s and above, and my worst one about 3230 kH/s and it wont go more because crashes the system....strange - I guess its just like humans - one better than other 
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Agree I have two 1080ti. One is an aorus extreme and is overclocked out of the box. 100% TDP -400 memory and +0 core it gets 3250 kh/s. My evga sc2 100% TDP -400 memory and a +60 core gets 3250 kh/s. I am unable to get 3300 per card like some people are the aorus has no more room and crashes if I put much more clock on it. I haven't tried to go further with the evga yet.))Difficulty still creeping up there on xzc. Almost 22000 now. Has jumped up a lot in the last week.